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    <title>Document</title>
    <script>
        var score = prompt('输入您的成绩');
        if (score >= 90) {
            alert('您的成绩为A');
        } else if (score >= 80) {
            alert('您的成绩为B');

        } else if (score >= 70) {
            alert('您的成绩为C');

        } else if (score >= 60) {
            alert('您的成绩为D');

        } else {
            alert('您的成绩为E')
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